Over the years, the purchasing habits of customers for starting, lighting and ignition ("SLI") batteries for automotive and other applications has changed. In the replacement market for SLI batteries, it has been increasingly the case that customers purchase such batteries at mass merchandisers and that warranties, often relatively expensive, are provided.
Accordingly, when a customer has problems starting this vehicle and suspects that the battery has gone bad, the customer returns the battery to the retailer or other location where the battery was purchased, and the warranty provided with the sale comes into play. A typical resolution is that the retailer takes the "bad battery" back, providing a new battery.
Indeed, it seems that the battery gets the blame as the cause for the problem regardless. Yet, it has been found that a significant proportion of batteries perceived as bad, and thus replaced per the warranty, are in fact lacking in charge, but capable of being recharged so as to provide satisfactory performance in use. The warranty cost to both the retailer or other battery seller and to the battery manufacturer is substantial.
For this reason, mass merchandisers and other battery sellers have turned to various types of testing devices in an attempt to effectively distinguish between good and bad batteries. Some battery testers which have been used carry out simple fixed discharges to determine battery power. Such testers are a variation of a standard load test in the industry which discharges the battery at half its cold cranking rate for 15 seconds and then looks for a minimum voltage adjusted for temperature to determine whether the battery being tested is good or not. While such a standard test is relatively simple and straightforward, this test requires that the battery be highly charged, a condition usually lacking in batteries that are giving problems for whatever reason and are thus perceived as being bad. Such a standard test also requires a large sustained discharge current which, of course, discharges the battery significantly. Many commercial diagnostic testing units include a fixed resistor which discharges all batteries at a close-to-constant rate that is well below the load test. Acceptable voltages are either fixed or relative to the cranking rate of the battery.
Testing units can also combine charging with the discharge test. Charging usually is done with a straight fixed voltage or current charger from a simple transformer with a rectifying diode which tries to force charge into the battery no matter what its condition. Yet, charging a battery can mask defects such as shorted cells and the like. Further, when batteries with shorted cells or bad internal connections are charged substantially, there can be a great deal of gassing and spewing of electrolyte which can be dangerous.
Another type of test unit proposed and used is a unit providing a conductance meter. Using relatively small current probes, the internal conductance of the battery is measured. This internal conductance is assumed to be proportional to the cranking rate of the battery, therefore providing a relative performance criteria. However, this type of test unit does not stress or polarize the battery enough to determine if there is sufficient power to sustain a discharge for more than a brief instant and cannot accurately predict the full-charge performance when the battery being tested is in a heavily discharged condition. Such an analysis also provides no information about the chargeability of the battery being tested.
Accordingly, despite the clear need for a highly discriminating lead-acid battery diagnostic test unit, it is believed that none of the types of test units being used satisfy the need. The warranty problem is a major issue in the lead-acid battery field which has simply not been solved.
Indeed, the situation is perhaps exacerbated by the increasing role mass merchandisers play in selling SLI and other lead-acid batteries. More particularly, the personnel responsible for dealing with battery returns not only do not have discriminating test units at their disposal, but are often less than adequately trained to deal with the many issues underlying whether a battery being returned is bad or good.
Still further, in many situations, the lack of patience of the customer can be evident. A decision as to whether the battery is good or bad needs to be capable of being provided in a relatively short period of time. Additionally, if the battery is determined to be good but in a discharged condition, then the customer will want to have the battery recharged in as short a time as possible.
Given the many and varied parameters that need to be addressed to allow a highly discriminating diagnostic testing regiment to take place and to rapidly recharge acceptable batteries, providing a suitable diagnostic test unit which can be safely used by the responsible personnel is a formidable task. Accordingly, it is a primary object of the present invention to provide a method and apparatus capable of rapidly discriminating between good and bad lead-acid batteries. A more specific object of this invention provides a test regiment capable of carrying out the appropriate determination in no more than 15, and still more preferably less than 10, minutes.
Another object lies in the provision of a diagnostic test unit capable of testing various types of lead-acid batteries having a variety of capacities as well as conditions while appropriately discriminating between good and bad batteries.
Still another object of the present invention provides a diagnostic test unit which can be operated by personnel with limited training at most.
Yet another object of the present invention provides a diagnostic test unit characterized by safety features which minimize, if not eliminate, safety issues as regards both users and as to the test units themselves.
A more specific object of this invention lies in the provision of a diagnostic test unit which includes an interactive charging unit capable of rapidly and reliably recharging lead-acid batteries.
Other objects and advantages will become apparent from the following detailed description.